diff --git a/src/resolve/test-resolved-etc-hosts.c b/src/resolve/test-resolved-etc-hosts.c
index b7dba0d780..c0b4b972c7 100644
--- a/src/resolve/test-resolved-etc-hosts.c
+++ b/src/resolve/test-resolved-etc-hosts.c
@@ -34,6 +34,7 @@ static void test_parse_etc_hosts(const char *fname) {
                 assert_se(fd >= 0);
 
                 f = fdopen(fd, "r+");
+                assert_se(f);
                 fputs("1.2.3.4 some.where\n", f);
                 fputs("1.2.3.5 some.where\n", f);
                 fputs("::0 some.where some.other\n", f);